Designed to operate from 1.8- to 5.5-V supplies, the op-amps suit a wide variety of portable medical applications, in which high accuracy and low quiescent current are critical. They are also well-suited for industrial applications, such as loop-powered systems, that require a combination of low power and precision.

System designers face the difficult task of scaling equipment that typically weighs upwards of 50 lbs, into portable form factors that weigh less than 10 lbs. They must also reduce equipment costs to enable dispersed deployment within the field, while minimizing power consumption to enable battery operation. And, because medical equipment comprises life-critical applications, designers must meet these requirements without compromising performance.

Op-amps that deliver precision and low-noise performance are key components in sensitive medical equipment. Since the front-stage amplifier must boost the biological signal several thousand times for display on a monitor, the amplifier must provide a very high common-mode rejection ratio; minimal 1ow-frequency noise; and ultra-low input-offset voltage, bias current, and input-voltage noise.

The device operates with all N-channel MOSFETs from inputs of 4.5 to 38 V and it can produce ±0.75%-accurate output voltages from 0.6 to 12.5 V. Output current is sensed by monitoring the voltage drop across the output inductor (DCR) or using a current-sense resistor.

A fixed operating frequency can be programmed from 250 to 770 kHz, or can be synchronized to an external clock with its internal PLL. The device's minimum on-time of just 90 ns suits the LTC3855 for high step-down-ratio applications.

Tracking and sequencing functions allow the optimization of power-up and power-down of multiple power supplies. Additional features include current-mode control, an onboard LDO for IC power, programmable soft start, two power good signals, and external VCC control.

The LTC3855 is available in a 38-lead SSOP or 40-lead 6- × 6-mm QFN packages. The LTC3855E, featuring an operating temperature range from -40° to 85°C, has a starting price of $3.18 in 1,000-piece quantities.

The LTC3855I industrial-grade version operates from -40°C to 125°C, with a 1,000-piece price starting at $3.59 each. Both versions are available from stock.Linear Technology Milipitas, CAwww.linear.com

1,500-W AC-DC Power Supply

THE HPU1K5 1,500-W ac-dc power supply series from XP Power targets industrial applications requiring bulk power within a compact enclosure. Three single-output models cover nominal output voltages of 12, 24, and 48 Vdc, with each being user-adjustable either manually or via an external voltage signal.

The universal input range covers 85 to 264 Vac, with available output power up to 1,500 W at high-line input, and up to 1,200 W when using input voltages below 180 Vac. Using an integral fan, the supply can be mounted vertically or horizontally and operates in temperatures from -20° to 50°C at full power, and up to 70°C with derating.

The mechanical design of the HPU1K5 includes a number of innovative design features, such as the use of a variable-speed fan to minimize audible noise, and the use of only two internal PCBs. These features aid the optimal flow of air through the unit, helping to maintain a low internal operating temperature and ensure long-term component reliability. A dual-stage PFC circuit and synchronous rectification contributes to the unit's 90% power efficiency.

The HPU1K5 can be used in current-share designs, where up to eight of the same output-voltage models can share current within 10% of each other at full load. A 5-V/1-A standby rail is standard. Other control lines and signals indicate AC OK, DC OK, Inhibit, Enable, Fan Fail, and overtemperature.

Remote sense compensates for up to a 0.5-V drop in connection cabling. All models have international safety agency approvals and meet required conducted and radiated noise levels. The HPU1K5 series comes with a three-year warranty and is available from Newark or direct from XP Power. The device is priced $507 in 500 pieces.XP Power Sunnyvale, CAwww.xppower.com

6-A Mini PoL Converter

FDK EXTENDS its DK Series of non-isolated PoL dc-dc converters with the PDK12TR8006PSV in an SIP package measuring 10.0 × 5.6 × 12.0 mm. The converter delivers up to 6 A output current at a power density exceeding 950 W/in3.

With an efficiency of up to 93%, the device provides a complete power-conversion solution without the need for external input and output capacitors. The converter suits a wide range of telecommunications, data communications, computing, industrial, and consumer applications where board space, cost, profile, efficiency, and reliable operation in elevated temperature environments are critical concerns.

Occupying a footprint of less than 0.6 cm2, the converter saves space over discrete on-board solutions. The low profile suits it for high-density racks, blade systems, and consumer applications with limited board-to-board and board-to-case clearances.

The FPDK12TR8006PSV operates from a 5.6- to 14.0-Vdc input and provides a tightly regulated programmable output voltage in the range of 0.8 to 6.6 Vdc. The converter is a true single-input device that does not require an external Vcc (bias) supply for operation.

At an output voltage of 3.3 Vdc, the converter delivers the full rated output current with no derating up to 65°C, with 400-lfm airflow. Other features include programmable output voltage, remote ON/OFF, overcurrent and overtemperature protection, and start-up into a pre-biased output.

All devices are RoHS compliant. In quantities of 1,000 pieces, the FPDK12TR8006PSV converters are priced at $5.70. Lead time is 8 weeks. Samples are available now.FDK San Jose, CAwww.fdk.com

20-V Power MOSFET

THE SIA433EDJ 20-V p-channel power MOSFET from Vishay Intertechnology offers on-resistance values of 18 mΩ at 4.5 V, 26 mΩ at 2.5 V, and 65 mΩ at 1.8 V. The 4.5- and 2.5-V RDS(ON) values are claimed to be 40% and 30% lower, respectively, than the closest competing p-channel device, and are said to offer the lowest on-resistances from a 2-mm2 footprint.

Packaged in a thermally enhanced PowerPAK® SC-70, the new MOSFET is built on TrenchFET® Gen III p-channel technology, which uses self-aligning process techniques to pack one billion transistor cells into each square-inch of silicon. This allows a superfine, sub-micron-pitch process that cuts the industry's best on-resistance for a p-channel MOSFET nearly in half.

The MOSFET is the only 20-V device with both a gate-source voltage of 12 V and an on-resistance rating at 1.8 V. This allows it to be used in applications that encounter higher gate-drive-voltage variations due to surges, spikes, noise, or overvoltages, while providing safer designs in applications with smaller input voltages.

The SiA433EDJ can be used as load, battery, and charging switches in handheld devices such as cell phones, smart phones, PDAs, and MP3 players. The low on-resistance of the MOSFET translates into lower conduction losses, saving power and prolonging battery life between charges in these devices.Vishay Intertechnology Malvern, PAwww.vishay.com

30-mm Brush DC Motors

A LINE of Pittman Series 8540 30-mm brush-commutated dc motors from Ametek integrate high-energy bonded neodymium magnets to maximize power density and offer an optimized magnetic-field profile. A seven-slot straight armature minimizes cogging. The motors additionally feature a large diamond-turned commutator and copper-graphite brushes to deliver high current capacity and long life.

The motors offer high torque-to-size performance to suit power data storage, medical equipment, and business machines, among other industry applications. With a 1.181-in. diameter, the dc motors come in standard lengths of 2.080 in., 2.552 in., and 3.025 in.

They are capable of continuous torque to 9.3 oz-in., continuous power to 43 W depending on model, peak torque to 78.7 oz-in, and speeds as high as 6,440 rpm at continuous torque for standard motors at rated voltages.

Feedthrough Terminal Block

THE 828 Series feedthrough terminal block from WAGO offers several industry-exclusive features to facilitate the feeding of up to 40 A (AWG 6) through enclosure walls. The feedthrough terminal block uses the company's Cage Clamp spring-pressure connection technology to ensure that all terminations are tool-free and maintenance-free. Users simply lift the lever, insert a stripped conductor (in sizes from 16 to 6 AWG) into the termination port and lower lever.

Rated at 300 V/40 A, the 828 Series features a one-piece construction to simplify the required panel opening and eliminate alignment issues during panel assembly. Installation is efficient: insert the block through a rectangular panel opening and secure it to the panel via a standard locking clip.

An exclusive integrated lockout feature accommodates a security seal or similar tag-out marker, limiting access to external terminations. A WAGO-exclusive panel gasket seal provides a splash-resistant seal to the enclosure for additional protection and reliability.

“Initially designed for use in alternative energy inverter systems, the tool-free simplicity of [the] 828 Series makes it ideal for applications where the field-wired power-input connections need to be segregated from sensitive electronics,” said Cory Thiel, WAGO product manager - interconnect. “The 828 Series feedthrough terminal block allows those power input connections to be made outside the protected area of an enclosure. Examples include HVAC control panels, lighting controls, generators, and more.”WAGO Germantown, WIwww.wago.com

PPTC Resettable Fuses

BEL FUSE Inc. has expanded its OZCx Series of SMT polymeric positive temperature coefficient (PPTC) resettable fuses. The RoHS-compliant, Pb-free and halogen-free fuses feature the company's unique polymer formulation to ensure long life and superior overcurrent protection for a variety of consumer electronic devices.

Offered in five EIA/IECQ case sizes ranging from 0805 to 2920, the chip fuses are rated to 60 Vdc with current ratings up to 3 A. The chips are specifically engineered to limit the flow of dangerously high current during fault conditions, protecting designs from overcurrent surges and overtemperature faults.

In the event of a fault, fuses reset themselves once power is removed; then, the fault is corrected and the voltage is reapplied. The devices' resettable functionality, coupled with unparalleled reliability, makes the OZCx Series a viable alternative to traditional fuses and fusible links.

Moreover, the devices support design flexibility and manufacturing efficiency while minimizing repair, service, and warranty expenses. Materials meet UL-94V-0 requirements. Boasting a fast trip time, the OZCx Series features an operating temperature range from -40° to 85°C.

Prices range from $0.08 to $0.20 each in production quantities, depending on case size, voltage, and hold current ratings. While delivery is from stock to 8 weeks, samples are immediately available.BelFuse Jersey City, NJwww.belfuse.com

DC-DC Module

THE PKM2810EPI from Ericsson is a 3.3-V/25-A-output dc-dc module that delivers up to 82.5 W. The module is the first device offered in the second generation of PKM2000EPI, complementing the company's portfolio to address the mid-power 24-V segment.

The module's high efficiency provides for a very good thermal derating performance, saving cost by simplifying thermal design. The module is principally aimed at telecom systems powered by 24-V batteries and accepts input voltages from 18 to 36 V.

However, because 24 V is common in industrial OEM applications such as process control, automation, robotics, and transportation, the product suits a wide range of applications. The device is also suitable when customers are upgrading boards to replace older modules to achieve higher efficiency levels.

Featuring versatile, useful controls, the module has an on/off control that is referenced to the input side (positive and negative logic options are available). A remote sense for the output voltage compensates for output distribution drops while the device's output-voltage trim range of 2.97 to 3.63 V permits custom voltages and voltage margining.

Because of its simplified design, low component count, and a high efficiency that reduces dissipated heat — according to Telecordia SR332 - Issue 1 - Black Box Technique — the PKM2810EPI has an MTBF of 1.5 million hours, guaranteeing excellent system reliability over its lifetime.

The product is compatible with the relevant clauses and requirements of the RoHS directive 002/95/EC, and fully meets requirements in high-temperature Pb-free soldering processes. In OEM quantities, price is $23.Ericsson Stockholm, Swedenwww.ericsson.com